Facebook Credits will be sold as a gift card at Best Buy and Walmart brick-and-mortar stores, just in time for holiday shopping.

Starting this week, staring at that last-minute rack of shiny candy wrappers and gift cards, shoppers will be able to pick up Facebook Credits in denominations of $10, $25 and $50 at Best Buy and $5, $10 and $25 at Walmart.

A month ago, Target stores were the first to start carrying Credits in gift card form.

“As we approach the holiday gift-giving season,” said a Facebook representative, “we’re happy to expand the availability of Facebook Credits gift cards to Walmart and Best Buy. More than 200 games and applications accept Facebook Credits, giving people a fun, convenient and secure way to buy premium items, and making Credits gift cards a unique gift for the holidays.”

The currency, which Facebook CEO Mark Zuckerberg has touted a couple times as a potential moneymaker for the aging social network, can be used to purchase virtual goods, like better harvesting technology in Zynga’s FarmVille or upgraded weapons in action games. (Facebook currently hosts a list of all the games and applications that let users purchase in-game goods with Credits.)

If Zuckerberg really intends on making Credits a ubiquitous currency, selling it as a gift card at these three huge retail stores is a great idea. In a way, it’s a form of marketing; for all those people who have never played a game on Facebook, Credits is still a completely foreign concept. It’s still more difficult to punch in a credit card number into a Web form to purchase something completely intangible than it is to just throw a small card into the checkout basket.

Facebook could be making some solid cash this holiday season, and not just by banking on the confused grandparent contingent (the grandchildren like that Facebook thing, right?).